Nowadays, various kinds of electric appliances have been invented, and bring much convenience and enjoyment to people. Electricity is required for the operation of electric appliances. However, hazards may occur due to breakdown of electric appliances, overload in use, damage of internal components or sparking of electric wires, among which sparking of electric wires is the most dangerous and causes the greatest harm.
Generally, sparking of electric wires results from improper use of electric appliances, common use of the same electrical outlet by several electric appliances, or breakdown of electric appliances. These problems cause an overload of the electric current in the electrical outlet and thus the hazard of sparking of electric wires. The results are catastrophic. Sparking of electric wires can damage the whole circuit system, and may endanger neighbors. In fact, many fires are caused by sparking of electric wires.
Usually, the electrical outlets on the wall of homes, public places and business offices are insufficient. Many people install an extension cord or a multi-electrical outlet in an electrical outlet for use of more electric appliances. Therefore, the electrical outlet bears a large load. When the load exceeds a certain value and the electrical outlet can bear no more, a short circuit or even sparking of electric wires occurs. R.O.C. Pat. No. 413,404 proposes an improved electrical outlet in which an overload protection circuit and a counter are used to cut off the power source when the electric current is overloaded. However, after the overload situation has been obviated, the normal function of power supply cannot be restored, hence causing inconvenience in practical application.